Seismic Analysis of Multistory Building with and without Floating Column
D_Chiu senior project draft
1. RADY ENGINEERING KPI Tower
Structural Design
Issue 16 December 2014
New Jersey Institute of Technology
Department of Civil and Environmental Engineering
CE495-Civil Engineering Design II
KPI Tower Structural Design
Prepared for:
Ala Saadeghvaziri
Methi Wecharatana
Prepared by:
Ryan Brennan
David Chiu
Ybrahina Cohen
Adam Guthartz
December 16, 2014
Proposal number: 123-4567
2. RADY ENGINEERING KPI Tower
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Acknowledgements
We would like to express our gratitude to our department and faculty, to our mentors and professors
Mr. Saadeghvaziri and Mr. Wecharatana for their guidance and constant support in the development
of this project. We would also extend our thanks to professor Santos and Professor Guzman and to the
many engineers who dedicated their time throughout this semester.
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Table of Contents
INDEX 5
EXECUTIVE SUMMARY 6
1 DESIGN PHILOSOPHY AND APPROACH 6
2 DESIGN SPECIFICATIONS 7
2.2 MATERIAL UNIT WEIGHTS 8
3 LOADING CRIT ERIA 9
3.1 DESIGN CODES AND FLOOR LOADINGS 9
3.2 GEOTECHNICAL CONDITIONS 10
3.3 CAR PARKING DECK 10
3.4 OFFICE FLOORS 10
4 STRUCTURAL DESIGN 11
4.1 ROOF DESIGN 12
4.2 FLOOR PLAN 13
4.3 CONCRETE SLAB 14
4.4 BEAMS 14
4.5 COLUMNS 19
4.6 STAIRS 25
4.7 FOUNDATIONS 25
5 CONCLUSION AND RECOMMENDATIONS 26
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Index
Ac- Area of Concrete, in2
Ag- Gross area of Columns, in2
As- Area of shear reinforcement, in2
As- Ratio of tension reinforcement
b- Web width of section, in.
d- Distance from extreme compression fiber to centroid of tension reinforcement, in.
F’y- Specified yield strength of reinforcement, psi
F’c- Specified compressive strength of concrete, psi
h- Height of beam section, in
Mn- Nominal moment capacity, kip-ft.
Mu- Factored applied moment, kip-ft.
Pu- Ultimate load
Vc- Shear strength of concrete, kip
Vn- Nominal shear strength of a section, kip
Vu- Factored applied shear, kip
w- Weight,lb
ρ max – Maximum ratio of reinforcement, in2
ρ max – Maximum ratio of reinforcement, in2
φ - Strength reduction factor
6. RADY ENGINEERING KPI Tower
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Executive Summary
The purpose of this report is to outline the design approach and philosophy of the KPI Tower
located in Bangkok, Thailand. The KPI Tower is a 24 story high rise building, estimated at a height of
296 ft., the KPI Tower includes 9 levels designated for parking space (levels 2-9), a lobby (level 1), 1
levels for mechanical equipment (Level 10), and 13 levels of typical office floors for office space
(levels 11-24).
1 Design Philosophy and Approach
The building was designed as an entirely reinforced concrete structure, with an entire glass
facade of curtain wall. This design was proposed as dictated by the governing codes: Minimum
Design Loads for Buildings and Other Structures (ASCE 7-10) and Building Code Requirements for
Structural Concrete and Commentary (ACI 318-11).
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2 Design Specifications
Beams
d = 2*b
h – d = 4
ρ = 2%
φ = 0.9
ω = ρ
F′
y
F′c
Mu = φ(F′
c × ω(1 − 0.59ω))(b × d2 )
Columns
ρ = 3%
φ = 0.9
P𝑢 = φ(0.85 × F′
c × As + ρ × Ag × F′
y)
Ag =
Ac
1−ρ
Slab
φ = 0.75
F’c=5000 psi.
F’y= 60,000 psi.
Mu =
w𝑙 𝑛
2
8
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Vc =
1.15 wuln
2
Vu = 2λ√F′c × b × d
Foundation
36 – Reinforced concrete piles on matt foundation
Diameter= 2.6 ft.
Length 178 ft.
2.2 Material Unit Weights
Table 2.2.1
Material Usage Unit Weight
Concrete Beams, Columns, Slabs 150
𝐥𝐛𝐬
𝐟𝐭
𝟑
Glass Facade Curtain Wall 203
𝐥𝐛𝐬
𝐟𝐭
𝟐
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3 Loading Criteria
3.1 DesignCodes and Floor Loadings
The KPI Tower was designed to meet the code requirements for structural concrete and loading
specifications as it dictated by ACI 318-11 and ASCE 7, respectively.
The dead and live loads used were as follow:
Table 3.3.1
Dead Load (DL)
in
𝐥𝐛𝐬
𝐟𝐭 𝟐
Live loads (LL)
in
𝐥𝐛𝐬
𝐟𝐭 𝟐
Combined Loads and
Factors (ASCE 7)
Factored loads in
𝐥𝐛𝐬
𝐟𝐭 𝟐
Roof 162.4 100 1.2(162.4)+1.6(100) 355
Parking Levels
Slab type A-B
Slab type B
40
110
110
110
40
40
.
1.2(110)+1.6(40)
1.2(110)+1.6(40)
.
196
196
Office Floors
Ground Floor
Slab type A
Slab type B
Slab type C
Mechanical Room
Stairs
7.
75
75
75
75
75
.
75
75
75
75
75
1.2(75)+1.6(75)
1.2(75)+1.6(75)
1.2(75)+1.6(75)
1.2(75)+1.6(75)
1.2(75)+1.6(75)
..
210
210
210
210
210
100
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3.2 Geotechnical Conditions
The KPI Tower stands on soft Bangkok clay, this type of clay has been well known for its high water
content, low shear strength and high compressibility. For construction a high rise building on such
clay, the main geotechnical concern are excessive settlement and potential stability failures. In order
to address such concerns, the KPI Tower foundation has been designed as a deep foundation
consisting of a matt footing1.
3.3 Car Parking Deck
The Design for the KPI tower includes a 9-level parking deck sufficient to accommodate 256 2
standard size vehicles. The slabs types corresponding to the parking deck are designed to carry a dead
load of 100
lbs
ft2 , a super imposed load of 10
lbs
ft2 and a live load of 40 psf. As per ASCE-7, the combined
factored loads yield 196
lbs
ft2
3.
3.4 Office Floors
Levels 11 through 24 are all designated to office space. As per ASCE-7, office floors required to
withstand an equal dead load and live load of 75 psf. This loading takes into consideration the dead
weight of office machinery, furniture and the live weight of people operating those floors. As per
ASCE-7, the combined factored loads yield 210
lbs
ft2 for the office floor slab4.
1
See section 4.6 onfoundations fordetails
2
Value obtainedfromEmporis buildingdirectory
3
Refer to table 3.3.1
4
Refer to table 3.3.1
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3.5 Stairs
The stair case for the KPI Tower runs from the ground floor to the 9th level of the parking deck with a
total of 16 landing slabs.
3.6 Mechanical Equipment Floor
Level 10 of the KPI Tower is entirely dedicated to equipment space, placing the mechanical
equipment room on higher leveled floors is very common among high-rise buildings such as this. The
mechanical equipment floor is designed to accommodate conditioning, electrical, chiller plants, water
pumps, and so on. The loading combination used for this floor are equal to the office floors above.
The loading combination proved to be conservative and adequate for the mechanical room
4 Structural Design
4.1 Roof Design
The roof was designed using 1 way slab principles, just as the rest of the building was done. There
are 2 types of critical slab loading for the roof, which we will distinguish by slab types A and B.
Type A runs West-East along the roof floor plan, and has a maximum span distance of 13.6 feet.
Type B is the critical cantilever section of the roof, which has a span distance of 9.8 feet.
Loading conditions were determined to be:
Self-weight of an 8” slab: 8”/12” x 150
lbs
ft2 is equal to 100
lbs
ft2
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Live Load of the Roof:
** There will be slots 1ft up from the parapet, which will allow any water greater than 1 foot to drain
off the sides should the drains get clogged. With this arrangement in mind, the maximum amount of
water that the roof would need to support would be 62.4
lbs
ft2
Roof Live Load: We used 100
lbs
ft2 to account for the live load on the roof, which exceeds the
governing roof load values set forth in IBC 1607.6 Helipads., which is 60
lbs
ft2 .
Therefore the total factored load for roof slab type A is 1.2(100+62.4)+1.6(100) which is 355
lbs
ft2
The ultimate moment was calculated to be Mu= 1/8(355)(13.6)2 which is equal to 8.2k-ft. Using our
excel calculator, we determined that an As of .26in2. However for simplicity, we will re-use the
typical slab type A, which has flexural steel of #4 bars at 6” total As is .4 in2 and S&T consisting of a
#4 at 18”.
For the cantilever section, the max moment was determined to be 17k-ft. Using our excel calculator,
the minimum As per 1 foot wide strip of the slab was determined to be .56 in2. Once again for
simplicity we will re-use the typical type B slab for the parking deck, which has flexural
reinforcement of #5 bars spaced at 4” a total As of .93in2. The S&T reinforcement will consist of #4
bars at 18” inches.
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4.2 Floor Plan
Although the KPI Tower has 24 different levels, its floor plan can be condensed into 13 types of
floors:
FP 1- Level 1 Ground Floor (lobby)
FP 2- Levels 2-9 Parking Deck
FP 3- Level 10 Mechanical Equipment Floor
FP 4- Typical office floor levels 11-16
FP 5- Floor level 17
FP 6-Floor level 18
FP 7-Floor level 19
FP 8-Floor level 20
FP 9-Floor level 21
FP 10-Floor level 22
FP 11-Floor level 23
FP 12-Floor level 24
The ground floor lobby, parking deck, mechanical equipment floor, and typical office floors and
levels 17 through 24 each have a different floor plan layout. The variety of floors in due to the
structure’s design, especially where the structure tapers in from levels 17 through 24.
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4.3 Concrete Slab
For the reinforced slab design of the KPI Tower, 3 different types of concrete slabs were proposed.
Each slab, Type A, B, C was specifically design to meet the specifications required as per each floor
type. Starting with the parking deck, a type A (non cantilever slab) and type B, a cantilever section
were designed. Following the same sequence, slab types A, B, and C were designed for floors 1, and
10 through 24.
Parking Deck Slab DesignType A (Non-Cantilever)
As per ASCE-7 Table 4-1, a design live load of 40
lbs
ft2 was used. Design dead loads include a
superimposed 10
lbs
ft2 load to account for any traffic signage, protective barriers or floor finishes that
might be applied to the parking deck structure in addition to the self-weight5.
Starting with an 8 inch slab, the slab-self weight was 100
lbs
ft2 the combined factor loads as dictated by
ASCE-7 were 196
lbs
ft2 . The Maximum moment yield was 4.5 kip-ft, with a required As (steel
reinforcement area) of 0.151 in2 per 1 foot width.
Check for shear capacity of concrete slab
The applied ultimate shear (Vu) was calculated as 1532.7 lbs per 1 foot width of slab. The shear of
concrete was calculated to be 11,879 lbs per with of slab. Phi x Vc= 8909 pounds per foot width.
Clearly the slab has adequate shear capacity. Based on a rho value that is above rho min below rho
5
See section 7.2Appendix C for slabdesign calculations for type A (non-cantilever)
15. RADY ENGINEERING KPI Tower
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max, we determined the best As value to be .4 in2 per 1 ft. wide strip. Reinforcement for flexural
strength was selected as #4 bars (As=0.2) spaced at 6” O.C. With a total reinforcement are of. 4 in2
Bar selection for Shrinkage and Temperature has resulted in #4 bars spaced at 18” O.C.
Parking Deck Slab Type B (Cantilever Section East-West)
The previously determined factored equivalent distributed load of 196
lbs
ft2 was used as well as a 0.203
kip point load representing the weight of the curtain wall on a 1 ft. wide strip, an ultimate moment of
20 kip-ft. was determined from structural
Using our excel spreadsheet calculator, the required As was determined to be 0.672 in2 for each 1 ft.
strip. Bar selection for flexural strength resulted in 4 #4 bars spaced at 3” O.C for a total area of steel
of 0.80 in2 per 1 foot strip. Bar selection for Shrinkage and Temperature resulted in #4 bars spaced at
18” O.C.
Typical Slab Type A DesignFloors 11-16
*Note: there are 3 types of slabs for floors 11-16, the primary slab going West-East across the long
span of the building (type A) as well as the cantilever slabs that exist on the Western and Eastern ends
of the building (Type C). The cantilever slabs are designed for the critical distance away from the
perimeter beam, which is 10.1 ft. (3.1 m). The last type is the cantilever slab 11.48 ft. (3.5 m) on the
north face of the floor plan. This is referred to as type B.
Slab Type A design
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Choosing 6 inches as a starting slab thickness, the slab self-weight was determined to be 75 psf. 6. The
curtain wall (facade material) was calculated as a dead load of 203 psf. As per ASCE-7, the combined
factored loads were calculated as 210 psf. ACI moment coefficients for critical values were used to
calculate a maximum moment of 4.0 kip-ft. This was determined to be a tension controlled section
with an area of reinforcement of 0.13
in2
ft
.
Check for shear capacity of concrete slab
The ultimate shear, was calculated as 3,284 lbs per foot of slab width, similarly concrete shear was
calculated as 7,212 lbs per slab width as well. Since the factored shear that the concrete can handle is
larger than the ultimate shear the concrete will experience the reinforcement area was designed with 3
#5 bars, with a total area of 0.93 in2. This done to ensure that our reinforcement ratio was well above
the minimum, while remaining below the maximum reinforcement ratio. With this area of
reinforcement, Mn was calculated to be 19.4 kip-ft., much greater than the maximum moment of 15.5
Kip-ft., as it was determined from the structural analysis. Therefore 3 #5 bars are adequate for the
slab.
ACI spacing requirements As minimum is .129
in2
ft
.
ACI 7.6.5 spacing requirements 3h or 18 inches.
Spacing required to get the 0.93
in
ft
6
Curtain Wall weight will be locatedalongtheperimeter ofthe slab, howeverit will be transferreddirectlytothe beamunderlyingit
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3#5 bars per 12” or 4” bar spacing O.C for flexural strength. Use #4 bars at 12 inches O.C for
shrinkage and temperature perpendicular to the flexural reinforcement.
Typical Slab Type B Designfloors 11-16
Using the already determined ultimate factored distributed load of 210
lbs
ft2 and a point load of 203
pounds from the curtain wall. The length of this cantilever section was taken to be 8.5 feet.
Using structural analysis software, the ultimate moment was determined to be -16.2 kip-ft.
Using our excel calculator, the required as per foot of slab was determined to be 0.86 in2.
3 #5 bars using 4” of spacing flexural strength yields an As of .93 in2 and this exceeds the spacing
requirements set forth in ACI 7.6.5.
Shrinkage and Temperature Transverse reinforcement
0.0018(12) (6) = .129
in2
ft
.
Typical Slab Type C DesignFloors 10-16
Using the factored distributed load of 210
lbs
ft2 and a point load of 203 lbs as it was previously
discussed for the slab type C.
The critical length taken for this analysis was 10.2 feet (3.1 meters). Using structural analysis
software, the ultimate moment was determined to be 15kip-ft, the required As per foot of slab was
determined to be 0.5 in2.
3 # 5 bars using 4” O.C spacing for flexural strength yields an As of 0.93 in2 and this exceeds the
spacing requirements set forth in ACI 7.6.5.
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Shrinkage and Temperature Transverse reinforcement
0.0018(12) (6) = 0.129
in2
ft
.
Using 1 #4 bar at 12 inches O.C for shrinkage and temperature perpendicular to the flexural
reinforcement.
Slab Design for floors 17 through 24
Each slab type previously designed (Types A, B, and C for floors 10-16) have been checked with the
beam layout and floor plans to work with floors 17-24.
For floors 17-24 there is the typical type A slab which spans East-West. Since the horizontal lengths
that the slab spans did not change over the course of the upper floors, the design conducted for floors
10-16 will also work.
The design for type A can be found below
Slab Type A: 3 # 5 bars therefore the area of steel is .93 in2 per 1 foot strip for flexural reinforcement.
Shrinkage and Temperature #4 bars @ 12” O.C
For floors 17-24 there is the typical type B slab which is a cantilever slab on the north part of the floor
plan. Its length is approximately 8.5 feet. This is the same as the previously designed floors therefore:
Slab Type B: 3 #5 bars using 4” spacing As is equal to .93 in2 per 1 foot strip for flexural
reinforcement.
Shrinkage and Temperature #4 bars @ 12” O.C
For floors 17-24 there is the typical type C slab which is a cantilever slab on the East West parts of
the floor plan. Its length is approximately 10.2 feet. The same design for this cantilever section
conducted for 10-16 will also be applicable here.
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Slab Type C: 3 #5 bars using 4” O.C spacing As is equal to of .93 inches per 1 foot strip for flexural
reinforcement and this exceeds the spacing requirements set forth in ACI 7.6.5.
Shrinkage and Temperature # 4 bars at 12 inches O.C
The ρ values for the slab conditions are (.93in2)/ (12”x4.625”) = .01675 or 1.675%. This falls within
the acceptable range of ρ min (.35%) and ρ max (2.52%) for flexure.
4.4 Beams
The beam design for the KPI Tower was based upon an excel sheet designed to generates the
maximum moment (k-ft.) 7 and area of steel reinforcement (in) required based on given beam
dimensions “b x d (in)”. The criteria established to generate this were the following:
d = 2*b
h – d = 4
ρ = 2%
φ = 0.9
ω = ρ
F′
y
F′c
Mu = φ(F′
c × ω(1 − 0.59ω))(b × d2 )
The next step in beam design was to lay out the beams on each floor in order to determine the critical
beam. The beam section determined to satisfy the critical beam for a floor was used in order to design
7
see Appendix C
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the majority of the beams on that specific floor. We did this for both vertical and horizontal beams (x-
z plane). For most cases, the slab design was the same, so for many floors the beam size was the same
as well. For floors 1-9 we used B-1 as our vertical beam design because it is supporting a cantilever in
addition to the slab, and B-12 as our horizontal beam design (these beam numbers our based on floor
2). RISA was used in order to determine the ultimate moment capacity for each critical beam.
8
This beam (B-1) is two spans beam with a length of approximately 7 feet, with a continued loading of
4.61. The maximum moment found was 473.3 k-ft., the beam chosen was a 14x28 that has a
maximum moment of 731.09 k-ft. (over designed). For the horizontal beam, the max moment of the
beam was determined to be a 716.6 k-ft. normally, the 14 x 28 beam would be adequate, but after over
design, the beam used was a 15 x 30 with a maximum moment of 899.21 k-ft.
8
Structural analysis for critical beam B-1 obtainedfromRISA for floors 1-9
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Floors 10-24 were established to have the same slab weight and also fit the criteria of the vertical
beam being a 14x28 and the horizontal beam being a 15x30 as shown with a sample of the horizontal
beam from floor 11:
9
The loading for this beam was 8.62
kip
ft
with two 16 kip point loads giving a maximum moment of
762.4 k-ft. This allowed the 15x30 beam to be adequate for the design. The same loading conditions
applied for the vertical beam where the maximum moment was to be 499 kip-ft. making the 14x28
adequate for that design. The one issue that arose with using these two beam types for every floor was
9
Structural analysis for critical beam B-1 obtainedfromRISA for floors 10-24
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the building getting narrower in the vertical direction. The columns get closer so in order to deal with
this, the beams on each floor had to become transfer beams and be able to hold the weight the
columns were holding. An estimate was taken off of an extremely large point load of 2000 kip-in
addition to the normal loading conditions placed near the column supports.
The maximum moment depicted was 2390.7 kip-ft. Transfer beams were required at floor 17 (they
were required from 18 upward though) the geometric section for transfer beams
10
10
Structural analysis for critical transferbeam obtainedfromRISA for floors 18-23
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was determined to be a 22x44 beam with a maximum moment of 2836.96 k-ft. After analyzing each
of the remaining floors, we noticed that each moment decreased by around 200 k-ft., so the beam
sections decreased for each remaining floor.
Floor 18 21x42 M = 2467.42 k-ft
Floor 19 20x40 M = 2131.45 k-ft
Floor 20 19x38 M = 1827.45 k-ft
Floor 21 18x36 M = 1553.83 k-ft
Floors 22-23 17x34 M = 1308.98 k-ft
Floor 24 did not require the transfer beam
These beams were placed only in between columns that moved closer together, thus the horizontal
beam design did not change.
Note that transfer beams were also required on floor 10 in replace of B-21 and B-22. The beam size
used is a 22x44 beam with a maximum moment of 2836.96 k-ft. This was used in order to carry the
weight of the stair columns which end on floor 10 and must be transferred on onto other columns.
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4.5 Columns
For the 24 story building, the columns were divided into 5 sections, each with 3 types of columns.
These sections were based upon similar beam layout. For each section, the lowest floor columns were
be designed, then applied to the floors above it. This ensured that the upper floors would have extra
support if needed and keep the column design more simplistic. The floor loading capacities were
based on the floor in which the columns are being designed for. For example, for section 18-23, the
columns designed for floors 18 through 23.
The column sections were determined for the following floors
Floor 1 columns
Floors 2-9 columns
Floors 10-17 columns
Floors 18-23 columns
Floor 24 columns
These 3 types of columns are:
C-A for the exterior columns that follow the perimeter of each floor.
C-B for the interior columns, basically all columns within the perimeter set up by the exterior
columns C-A.
C-C fort the two columns used to support the stairs. C-C columns are smaller than C-A and C-B.
For each of these column types, on the floor section used a critical column was determined and
designed for. The critical column supports the most weight for that type and, the geometric section
that satisfied the loading conditions of the critical column was applied to every column for that type in
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this section. The columns used for section C-A were determined to be C-7 for floors 1 through 9 since
these supported the cantilever section and C-9 from floor 10 to 24, For type C-B, the columns used C-
3 for floors 1 through 9 (due to the fact the stair columns C-C end and are transferred onto C-3 and C-
4 by transfer beams) and C-10 for floors 10 through 24. For C-C column C-4 was used from floors
10-24 which are the only floors that contain these stair columns.
4.6 Stairs
4.7 Foundations
The foundation for the KPI Tower was designed as a matt foundation sitting on reinforced concrete
pile. It was determined that 38 reinforced concrete piles are needed in order to support the loading
imposed by the structure. The piles were designed to be 2.6 ft. in diameter and 174 ft. in length.
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5 Conclusion and Recommendations
The structural design for the KPI Tower was made simple by identifying each critical section and
developing a design that would satisfy that specific section. Once the final design was developed, it
was applied to similar members. This “critical section approach” allowed for a very conservative
design. All of the design members were in accordance with ACI-318 for reinforced concrete as well
and ASCE-7 for loading combinations.
This project was challenging in many aspects; Beginning from the foundation since the properties of
Bangkok clay are unfavorable for most developments. Due to this condition the KPI Tower
foundation was designed as a reinforced concrete matt foundation sitting on 34-2.6 ft. wide reinforced
piles, driven 174 ft. into the clay soil.
Other challenges came from the building’s structural aspect, the developing of cantilever beams and
slabs in order to accommodate the building’s architectural design.
The design of the KPI Tower was very complex, requiring that we revisit aspects of Reinforced
Concrete Design in beams and columns, Deep Foundations Design in clay as well as exposing us so
new design approaches, such as cantilever slabs and beams.
Although we are not ready to design such a high-rise building like the KPI Tower, we now have a
better understanding on how these building are design, and what are some of the challenges that we
may face in the future.
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6 Self-Learning
As this semester comes to an end, it is time to reflect on the things we have learned thus far. This
challenging project required that we utilize every resource available in our reach; our professors,
books, publications and engineering software.
Among these resources we had access to publications from the American Institute of Concrete
Commentary on Building Code Requirements for Reinforced Concrete (ACI 318-63) as well as the
American Society of Civil Engineers ASCE 7-10 Minimum Design Loads for Buildings and Other
Structures. This project allowed us to familiarize ourselves with design codes that mandate every
structure in the United States as well as in many parts of the world. Learning how to interpret such
codes is very important in our professional careers. We must always be aware that the welfare of the
people depends on the choices that we, as Civil Engineers, make. It is ethically and morally important
that we follow and comply with these codes to the absolute best of our abilities.
This design project also required the extensive use of computer programs, among these were:
AutoCAD and REVIT for structural drawings, and RISA for structural analysis and design. Gaining
experience in these programs is highly important to become qualified and competent in our field.
Knowing how to use these programs allows us to perform complicated design in a much more
efficient way. Although these are just a few of the things we have learned at the moment, most of our
learning will be reflected once we practice in the field when we are challenged with a real life
problem that we must solve. One of the lessons that we must take away is the ability to use our
resources, and even if we don’t know something at the moment, it is important to know where to find
it.
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7 References
ASCE 7-10 Minimum Design Loads for Buildings and Other Structures.10th ed. American Society of
Civil Engineers. 2010. Print.
Commentary on Building Code Requirements for Reinforced Concrete (ACI 318-11) Report of ACI
Committee 318, Standard Building Code. 11th ed. Detroit: American Concrete Institute, 2011.
Print.
MacGregor, James G., and James K. Wight. Reinforced Concrete: Mechanics and Design. 5th ed.
Upper Saddle River, N.J.: Prentice Hall, 2009. Print.
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8 Appendices
8.1 Appendix A: Floor Plan
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8.2 Appendix B: Slab Design Calculations
Parking Deck Slab Design Type A (Non-Cantilever)
8” slab starting point:
d=8”-.75”cc-.25”= 7”
Slab self-weight= 8”/(12”/1ft) x150 lb./ft3 = 100 lb./ft2
Factored Load combinations:
1.2(100+10)+1.6(40)= 196 lb./ft2
Mu=(196)(13.6ft)2/8 = 4.5 k-ft.
Using our excel spreadsheet calculator, the required As was determined to be .151 in2 per 1 foot
width.
Check for shear capacity of concrete slab:
Vu= 1.15(196 lb. /ft2) (13.6ft)/2 = 1532.7 pounds per 1 ft. width of slab.
VC=2(1) (12”) (7”) =11,879 pounds per 1 ft. width of slab.
φ Vc= 8909 pounds per foot width. Clearly the slab has adequate shear capacity.
Keeping a tension reinforcement value that is above ρmin below ρmax, we determined the best
as value to be .4 in2 per 1 ft. wide strip.
Bar selectionfor flexure has resulted in #4 bars (As=.2) spaced at 6” O.C. Total As is now .4 in2
Bar selectionfor Shrinkage and Temperature has resulted in #4 bars spaced at 18” O.C.
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Slab type A
Floor slab thickness starting point chosen as 6” thick.
Using (#5 bars) determined later in the design,
the d=6”-.625”-.75”=4.625”.
Slab self-weight is 6”/12”*150 lb/ft^3 = 75 lb/ft^2
**Curtain Wall weight will be located along the perimeter of the slab, however it will be transferred
directly to the beam underlying it.
Curtain wall weight calculations for beam design (include as a dead load): curtain wall critical
length= 8.3 meters, which is 27.2 feet.
Critical height is 3.8 meters which is 12.46 feet.
Glass thickness estimated to be 1.5” thick, which is .125 feet. Unit weight of glass taken to be 130
lb/ft^3. (27.23)(23.46)(.125)=42.41 ft^3 of glass x 130 lb/ft^3= 5513 pounds.
Taking this weight and dividing it over the area of 27.2 feet yields the curtain wall dead load of 203
lbs/ft.
Live Load of 75 pounds per square foot for office building design as per ASCE 7 Table 4-1. Dead
Load of slab is 75lb/ft^2
Factored 1.2D+1.6L= 1.2x (75)+1.6x(75)=210 psf.
ACI Moment coefficients critical value of -1/10, to determine the moment value.
Mu is -1[(210) x (1’) x (13.6)2/10] is roughly 4 k-ft.
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As > (4x12”/ft)/(.9x60x.95x4.625) which is .20 in2 per foot.
a= (.20)(60)/(.85x5x12) which equals .15 inches.
Another iteration to determine a more accurate As value
As = (4*12)/(.9*60)(4.625-.15) which equals .13 square inches per foot.
Check tension controlled: 3/8 of d is 1.73” c (a/beta)=(.15/.8) is significantly lower than 1.73,
therefore tension controls and phi is correctly assumed to be 0.9.
Shear Designfor Slab
Vu= (1.15wuln) /2 yields (1.15x210x27.2)/2 is equal to 3,284 lbs per 1ft width of slab.
Vc= 2(1)(sqrt(5000)(12)(4.25) which is equal to 7,212lbs per 1 ft width of the slab.
Phi is .75 so Phi Vc is equal to 5,409lbs.
The factored shear that the concrete can handle is larger than the ultimate shear the concrete will
experience. This done to ensure that our reinforcement ratio was well above the minimum, while
remaining below the maximum reinforcement ratio.
Mn (.93)(60)[4.625-.45] which is 19.41 k-ft, where the moment determined to be max from structural
analysis is 15.5 k-ft. Therefore 3 #5 bars will work.
ACI spacing requirements As min is .0018x12x6 is .129 in2/ft
ACI 7.6.5 spacing requirements 3h is 18 inches or 18 inches.
Spacing required to get the 0.93 inches per foot is 3 #5 bars per 12” or 4” bar spacing O.C Flexural
This value exceeds the ACI 7.6.5 requirement.
Shrinkage and Temperature transverse reinforcement.
As S&T which = .0018(12)(6)= .129 in/ft2
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Use #4 bars at 12 inches O.C for shrinkage and temperature perpendicular to the flexural
reinforcement.
Typical Slab Type B Designfloors 11-16
Using ultimate factored distributed load of 210 psf. or .210k/ft.
A point load of 203 pounds or .203 kips representing the curtain wall dead load sitting at the edge.
The length of this cantilever section was taken to be 8.5 feet. Using structural analysis software, the
ultimate moment was determined to be -16.2k-ft or 194k-inches. Using our excel calculator, the
required As per foot of slab was determined to be 0.86 square inches. 3 #5 bars using 4” of spacing
flexural strength yields an As of .93 inches square and this exceeds the spacing requirements set
forth in ACI 7.6.5.
Shrinkage and Temperature Transverse reinforcement .0018(12)(6)=.129 inches square/ft.
1 # 4 bar spaced at 12” O.C for shrinkage and temperature perpendicular to the flexural
reinforcement.
Typical Slab Type C DesignFloors 11-16
Using ultimate factored distributed load of 210 psf or .210 kip/ft.
A point load of 203 pounds or .203kips representing the curtain wall dead load sitting at the edge.
The critical length taken for this analysis was 10.2 feet, or 3.1 meters.
Using structural analysis software, the ultimate moment was determined to be –15k-ft or 180 k-
inches.
Using excel, the required As per foot of slab was determined to be .5 square inches.
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3 # 5 bars using 4” O.C spacing for flexural yields an As of .93 inches square and this exceeds the
spacing requirements set forth in ACI 7.6.5.
Shrinkage and Temperature Transverse reinforcement
.0018(12) (6)= .129 inches square /ft.
Using 1 #4 bar at 12 inches O.C for shrinkage and temperature perpendicular to the flexural
reinforcement.
Slab Design for floors 17-24 will be similar to those used in floors 11-16
Slab Type A: 3 # 5 bars therefore the area of steel is .93 in2 per 1 foot strip for flexural
reinforcement.
Shrinkage and Temperature #4 bars @ 12” O.C
Slab Type B: 3 #5 bars using 4” spacing As is equal to .93 in2 per 1 foot strip for flexural
reinforcement.
Shrinkage and Temperature #4 bars @ 12” O.C
Slab Type C: 3 #5 bars using 4” O.C spacing As is equal to of .93 inches per 1 foot strip for
flexural reinforcement and this exceeds the spacing requirements set forth in ACI 7.6.5.
Shrinkage and Temperature # 4 bars at 12 inches O.C
The Rho values for the slab conditions are (.93in2)/ (12”x4.625”) = .01675 or 1.675%. This falls
within the acceptable range of rho min (.35%) and rho max (2.52%) for flexure.
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8.3 Appendix C: Beams Figures Calculations
The complete beam table details:
The beam’s name with respect to the design drawings
The number of spans
The number of supports
The length of the beam
The beams dimensions in b x d
The beams dimensions in b x h
The area of steel needed
The bar size chosen
The area of steel based on the bars chosen
The programs used in order aid with the beam design were:
RISA – used to determine the max moment of the beam
Revit – used to do the base design of the of building
Autodesk AutoCAD Civil 3D 2015 – used to do the drawings of the various of cross sections
Excel – in order to organize all the data
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Table 8.3.1-Beam Organization Sheet
Beam
Section
sType
Beam
Section
s b,d
in^2
Beam
Section
s b,h
in^2
Area of
Reinforcement
in^2
Reinforcement Bars Area
in^2
Stirrups
A 14x28 14x32 7.84 8#9bars, 2rows 8 #6@s=11d-away from support; #10@s=12inches; #6@s=11inches d way from support
B 15x30 15x34 9 10#9bars, 2rows 10 #6@s=11d-away from support; #10@s=12inches; #6@s=11inches d way from support
C 17x34 17x38 11.56 10#10bars, 2rows 12.7 #6@s=11d-away from support; #10@s=12inches; #6@s=11inches d way from support
D 18x36 18x40 12.96 12#10bars, 2rows 15.24 #6@s=11d-away from support; #10@s=12inches; #6@s=11inches d way from support
E 19x38 19x42 14.44 12#10bars, 2rows 15.24 #6@s=11d-away from support; #10@s=12inches; #6@s=11inches d way from support
F 20x40 20x44 16 12#11bars, 2rows 18.72 #6@s=11d-away from support; #10@s=12inches; #6@s=11inches d way from support
G 21x42 21x46 17.64 12#11bars, 2rows 18.72 #6@s=11d-away from support; #10@s=12inches; #6@s=11inches d way from support
H 22x44 22x48 19.36 21#9bars, 3rows 21 #6@s=11d-away from support; #10@s=12inches; #6@s=11inches d way from support
F 24x48 24x52 23.04 24#9bars, 3rows 24 #6@s=11d-away from support; #10@s=12inches; #6@s=11inches d way from support
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8.4 Appendix D: Columns
In order to calculate the area of concrete for the column (Ac) the equations
The loading on the columns is due to:
The live load
The slab self-weight
The beam self-weight
The column self-weight
For floors 18-23, transfer beams are required in order to support the weight of the columns since the
columns get closer as the floors go higher. These transfer beams vary in size depending on the floor
and are only located in between the first and last row columns
Transfer beams are also required on Floor 10. The columns that support the stairs end so the beam
will transfer to C-A columns below it.
The excel chart is split into several sections
• “Previous Floor Weight” represents the total weight of the floors above.
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• “Estimated Weight per floor” is based on the critical floor’s weight determined by live load,
slab self-weight, and beam self-weight. This is multiplied by as many floors there are in the
section to get a rough estimate of the total weight of floors in the section. The first floor in the
section is not included since it is below the columns of that floor. Thus that floor is added to
the next section.
• “Column Weight” is the self-weight of the critical column. This is multiplied by the amount of
floors in this section in order to include the columns directly above it.
• “Total Pu” is the ultimate load. This is the combination of the “previous floor weight” the
“Estimated weight per floor” multiplied by the correct amount of floors, and the “column
weight” multiplied by the columns directly above each other in this section.
• “Area of Concrete” is the calculated area of concrete.
“Gross Area” is the total area of the section.
“Area of Steel” is the area of steel required based off 0.3% rho.
“Bars required” what size bars are needed for the column.
“Area of Steel required” is what the area of steel of those bars are.
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Table 8.4.1- Columns
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8.5 Appendix E: Stairs
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8.6 Appendix F: Foundations
